Flocculation of the yeast Candida famata (Debaryomyces hansenii): An essential role for peptone

Aggregation of Candida famata (Debaryomyces hansenii) is consistent with being a form of lectin-mediated yeast flocculation. Flocculation of C. famata is unusual in that it requires the presence of peptone, either in the growth medium or added later to harvested cells in buffer. Flocculation after peptone addition was rapid, being largely complete within 10 min. Heat-killed cells also flocculated, arguing for direct participation of peptone in the flocculation binding mechanism. Flocculent C. famata cells progressively lost the ability to flocculate when washed with EDTA. Flocculation was fully restored by peptone addition; calcium addition was without effect. C. famata cells were able to agglutinate erythrocytes in the presence or absence of peptone. Pronase E-treated yeast lost both the ability to haemagglutinate and self-flocculate. Haemagglutination was not diminished by progressive EDTA washing, suggesting that surface lectins remained present and active on the yeast cell walls. Non-flocculating C. famata cells mutually flocculated with non-flocculent Schizosaccharomyces pombe cells, shown to have surface-exposed galactose residues. Mutual flocculation was lost following treatment of C. famata with Pronase E. It was concluded that the cell wall of C. famata contains lectins enabling haemagglutination and mutual flocculation but lacks carbohydrate receptors for these lectins. This yeast self-flocculates only via bridging multi-valent carbohydrates; these being present in peptone.     

Shear Analysis of Concrete with Brittle Reinforcement

The design of steel-reinforced concrete relies on lower-bound plasticity theory, which allows an equilibrium-state to be postulated without considering compatibility. This is of particular benefit in shear design, due to the complexity of shear-transfer, where simplified models such as the truss analogy are used. Lower-bound plasticity theory, however, relies on stress-redistribution. If brittle reinforcement [such as fiber-reinforced-plastic (FRP)] is used in concrete, lower-bound plasticity theory cannot be applied. This paper studies how compatibility, equilibrium, and the material constitutive laws can be combined to establish the actual conditions within an FRP-reinforced beam subjected to shear. A crack-based analysis is proposed to model shear failure in a beam with brittle reinforcement. The analysis is used to illustrate the importance of satisfying compatibility requirements, and the results are contrasted with the current shear design proposals for FRP-reinforced concrete.     

Sensitivity to change of the Roland-Morris Back Pain Questionnaire: part 1

BACKGROUND AND PURPOSE: This study estimated the Roland-Morris Back Pain Questionnaire's (RMQ) change score that best classified patients as those who had achieved an important change and those who had not achieved an important change. The study also investigated whether the estimate of change was dependent on patients' initial scores. Subjects and METHODS: The RMQ was administered to 226 patients with low back pain of less than 6 weeks' duration during their initial visit for physical therapy and following 3 to 6 weeks of treatment. A global rating of change was used to classify patients as those who had changed an important amount and those who had not changed. Receiver operating characteristic curves were used to identify the RMQ change score that most accurately classified patients with respect to important change. This analysis was repeated for 5 overlapping subsamples of patients with initial scores 0 to 8, 5 to 12, 9 to 16, 13 to 20, and 17 to 24. RESULTS: The area under the receiver operating characteristic curves increased when patients' initial scores were taken into account. Estimates of important change were 2, 4, 5, 8, and 8 for the initial score intervals mentioned above. CONCLUSION AND DISCUSSION: Important change appears to be dependent on patients' initial RMQ scores. Subsequent inquiry using different hypotheses would add support to the estimates of important change found in this study.     

Behaviour of a masonry arch bridge repaired using fibre-reinforced polymer composites

This paper describes a series of laboratory tests investigating the behaviour of a large model masonry arch bridge repaired with externally bonded fibre-reinforced polymer (FRP) on its intrados. Many similar masonry arch bridges form critical links in the world’s transport infrastructure, but they are often not suited to the increased demands of modern traffic loading, especially in ageing arch structures that have suffered structural deterioration. FRP plates, adhesively bonded to the intrados of the masonry arch are a convenient method for strengthening arch bridges. The tests described in this paper demonstrated that FRP strengthening is an effective technique for improving the structural performance of a masonry arch bridge.A two-span, single-ring semi-circular brick arch bridge was tested in this study, complete with fill material. Each of the spans was initially loaded to investigate their response and to establish a four-hinge collapse mechanism, simulating damage prior to strengthening. FRP strengthening was then applied to the two arches, and each of the spans was again tested separately until the failure of the strengthening system. The global (load and deflection) and local (crack width and FRP strain) response of the structure was recorded. The FRP strengthening resisted flexural crack opening in the masonry, and hence prevented a four-hinge mechanism collapse. Failure instead occurred when the FRP strengthening debonded from the masonry adjacent to an existing intrados hinge crack. As well as shear debonding adjacent to flexural cracks in the masonry, peel debonding occurred where shear deformation occurred across a masonry crack. Catastrophic collapse did not occur, as the FRP continued to contribute to the load capacity by acting as a tie after the ultimate load had been reached.     

Harmonic Pollution on Power Systems?A Change in Philosophy

Static power converters have increased in number and uses in the past decade, and there has been an increased use of static power capacitors for improving power factor. These two trends have set, the stage for possibly uncontrolled harmonic resonances on industrial power systems. Some example of some problems are given and some practices are recommended, in line with a new IEEE standard, that will minimize the chance of harmful resonant conditions.     

S-2-amino-5-azolylpentanoic acids related to L-ornithine as inhibitors of the isoforms of nitric oxide synthase (NOS)

To characterize the importance of a highly conserved region of the class II beta chain, we introduced an amino acid substitution that is predicted to eliminate a hydrogen bond formed between the class II molecule and peptide. We expressed the mutated beta chain with a wild-type alpha chain in a murine L cell by gene transfection. The mutant class II molecule (81betaH-) assembles normally in the endoplasmic reticulum and transits the Golgi complex. When invariant chain (Ii) is coexpressed with 81betaH-, the class II-Ii complex is degraded in the endosomes. Expression of 81betaH- in the absence of Ii results in a cell surface expressed molecule that is susceptible to proteolysis, a condition reversed by incubation with a peptide known to associate with 81betaH-. We propose that 81betaH- is protease sensitive because it is unable to productively associate with most peptides, including classII-associated invariant chain peptides. This model is supported by our data demonstrating protease sensitivity of peptide-free wild-type I-Ad molecules. Collectively, our results suggest both that the hydrogen bonds formed between the class II molecule and peptide are important for the integrity and stability of the complex, and that empty class II molecules are protease sensitive and degraded in endosomes. One function of DM may be to insure continuous groove occupancy of the class II molecule.     

Thymidine phosphorylase moderates thymidine-dependent rescue after exposure to the thymidylate synthase inhibitor ZD1694 (Tomudex) in vitro

The inhibition of de novo thymidine (dThd) synthesis by the novel folate-based thymidylate synthase (TS) inhibitor ZD1694 (Tomudex) can achieve tumor cell-specific cytotoxicity in vivo. However, nucleosides in the surrounding microenvironment of tumors may be used by the salvage pathway to regenerate any depleted pools, thus providing an efficient mechanism through which to circumvent the ZD1694-dependent toxicity. Anabolism of dThd to dTMP by dThd kinase (TK) is the first committed step in the dThd salvage pathway. However, dThd phosphorylase (dThdPase) can compete with TK by catalyzing the reversible phosphorolytic cleavage of dThd to thymine and deoxyribose 1-phosphate and rendering the salvaged dThd metabolically unavailable. Both TK and dThdPase are up-regulated in some tumors, and their relative importance is not fully defined. We have studied the influence of dThdPase expression on the capacity of exogenous dThd to reverse ZD1694-dependent growth inhibition and have shown that both intra- and extracellular dThdPase activity can effectively moderate dThd-rescue. This suggests that tumor levels of dThdPase may be an important factor in the outcome of ZD1694 therapy.     

Student perceptions of a virtual field trip to replace a real field trip

Abstract  This study examines student perceptions on the use of virtual field trips (VFT) as part of their university experience and in particular the extent to which they could replace real field trips. While students were extremely positive about the potential of VFT to provide valuable learning experiences (and in particular a VFT constructed by the authors of this paper) nearly all of the students were insistent that it could not, and should not, replace real field trips. Furthermore when the same students were re-approached after having been on a real field trip, these perceptions were strengthened and they thought VFT could be most effective in preparing for, or revising after, a real field trip.     

Storage and the electricity forward premium

We develop and test a model describing the influence of natural gas storage inventories on the electricity forward premium. The model is constructed by linking the effect of gas storage constraints on the higher moments of the distribution of electricity prices to an established model of the effect of those moments on the forward premium. The model predicts a sharply negative effect of gas storage inventories on the electricity forward premium when demand for electricity is high and space-heating demand for gas is low. Empirical results, based on PJM data, strongly support the model.